The present invention rlates to a self-regulating solar window device for controlling the transmission of solar radiation to an area, and to active and passive solar collector systems employing such a solar window.
The harnessing of solar energy for the efficient generation of heat and electricity is assuming increased importance in light of growing awareness of the limited nature of our fossil fuel resources. Active solar collector systems, utilizing circulating fluids as the heat transfer mechanism, and passive solar collector systems, relying on the absorption and re-radiation of solar energy by a stationary collector surface, are both well known. However, techniques for increasing the efficiency and effectiveness of such systems are being sought. The window device of the present invention provides an improved technique for more effectively controlling the transmission of incident solar radiation to the collector surfaces of such systems.
The solar heating device described in U.S. Pat. No. 3,884,414, issued May 20, 1975, utilizes a plurality of pivotable louver panels. One of the louver panels is provided with exterior and interior pressure cannisters which are interconnected to control both the opening and closing of the panels. An expansible fluid such as freon is provided in the cannisters. When the exterior cannister is exposed to direct sunlight such that the temperature of the exterior cannister is greater than that of the interior cannister, the relative vapor pressure of the freon in the exterior cannister increases, thereby forcing freon from the exterior cannister to the interior cannister until the vapor pressures are stabilized. As a result, the weight of the exterior cannister decreases and the weight of the interior cannister increases, causing the control panel and slave panels connected thereto to open. An opposite series of events takes place when the internal temperature of the exterior cannister is less than that of the interior cannister.
This type of solar heating device seeks merely to add energy to the interior of a structure above the ambient energy level contained therein, and does not seek to maximize solar energy transfer at levels of transmission lower than the ambient of the structure's interior. Furthermore, the applicability of such a device is limited to areas specifically designed to absorb massive energy transmissions. Also, this prior art device does not provide automatic protection against overheating, and will permit a constantly changing level of solar insolation to enter the building, i.e. it is unregulated.
U.S. Pat. No. 3,860,055, issued Jan. 14, 1975, discloses a shutter device for raising, lowering and adjusting the inclination of conventional window shutters. This device has a transducer element containing an expansible material, such as a gas at a slight overpressure, which activates a piston-cylinder unit for operating a cam-lever arrangement. The cam-lever arrangement cooperates with a mechanism for adjusting the inclination of the shutters.
One problem inherent in this type of device is that it is unresponsive to the amount of solar radiation actually passing through the shutters. This follows from the fact that the transducer element is situated between the window glass and the shutters. Another disadvantage is that the transducer element of this device will measure the same level of solar energy at different sun heights. Thus, total internal reflection of the window surface will not be accounted for by this prior art device. Additionally, such a device is not designed for absolute regulation of solar radiation transmission, since the transducer element is not insulated from the interior energy level.
This device, as with the device disclosed in U.S. Pat. No. 3,884,414, is designed for operation at a single ambient temperature (as for example in climate-controlled buildings), and is not readily adjustable over a range of temperatures.